super(32)P-postlabeling of DNA adducts arising from complex mixtures: HPLC versus TLC separation applied to adducts from petroleum products

The carcinogenicity of petroleum products is mainly due to their content of polycyclic aromatic compounds (PACs). These compounds may be activated metabolically and react with DNA to form DNA adducts, which is a critical event in the initiation of cancer. One of the most common techniques for analyzing DNA adducts is super(32)P-postlabeling. The chromatographic method often used has been super(32)P-TLC (thin-layer chromatography), but the more recently developed super(32)P-HPLC (high-performance liquid chromatography) method has shown advantages. The aim of this study was to test the hypothesis that the super(32)P-HPLC method has a better ability of detecting DNA adducts derived from petroleum products than super(32)P-TLC. It was found that some DNA adducts migrated from the application point in super(32)P-TLC in such a way that it is doubtful if they could be detected and quantified properly. It was also found that, when using super(32)P-HPLC, it is possible to use the same protocol for substances with a wide variety of DNA adduct forming potential, whereas super(32)P-TLC needs to be optimized regarding time of exposure and/or the amount of DNA applied. Further, a pattern of recognition in super(32)P-HPLC enables a selective assessment of DNA adducts derived from complex mixtures whereas super(32)P-TLC is very limited when analyzing complex mixtures due to poor resolution. With more knowledge about the properties of the most mutagenic DNA adducts in HPLC, it could be possible to know also which pattern corresponds to a mutagenic or carcinogenic oil. Consequently, super(32)P-HPLC is a good alternative when assessing the genotoxicity of petroleum products.